<!--$Id: env_set_lk_detect.so,v 10.50 2006/02/27 14:51:30 bostic Exp $-->
<!--Copyright (c) 1997,2008 Oracle.  All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB: DB_ENV-&gt;set_lk_detect</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
</head>
<body bgcolor=white>
<table width="100%"><tr valign=top>
<td>
<b>DB_ENV-&gt;set_lk_detect</b>
</td>
<td align=right>
<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a>
<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
</tr></table>
<hr size=1 noshade>
<tt>
<b><pre>
#include &lt;db.h&gt;
<p>
int
DB_ENV-&gt;set_lk_detect(DB_ENV *dbenv, u_int32_t detect);
<p>
int
DB_ENV-&gt;get_lk_detect(DB_ENV *dbenv, u_int32_t *lk_detectp);
</pre></b>
<hr size=1 noshade>
<b>Description: DB_ENV-&gt;set_lk_detect</b>
<p>Set if the deadlock detector is to be run whenever a lock conflict
occurs, and specify what lock request(s) should be rejected.  As
transactions acquire locks on behalf of a single locker ID, rejecting a
lock request associated with a transaction normally requires the
transaction be aborted.</p>
<p>The database environment's deadlock detector configuration may also be configured using the
environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file.  The syntax of the entry in that
file is a single line with the string "set_lk_detect", one or more whitespace
characters, and the method <b>detect</b> parameter as a string; for example,
"set_lk_detect DB_LOCK_OLDEST".
Because the <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment
is opened, it will silently overrule configuration done before that
time.</p>
<p>The DB_ENV-&gt;set_lk_detect method configures a database environment, not only operations
performed using the specified <a href="../api_c/env_class.html">DB_ENV</a> handle.</p>
<p>The DB_ENV-&gt;set_lk_detect method may be called at any time during the life of the
application.</p>
<p>The DB_ENV-&gt;set_lk_detect method
returns a non-zero error value on failure
and 0 on success.
</p>
<b>Parameters</b> <br>
 <b>detect</b><ul compact><li>The <b>detect</b> parameter configures the deadlock detector.  The
specified value must be one of the following list:
<br>
<b><a name="DB_LOCK_DEFAULT">DB_LOCK_DEFAULT</a></b><ul compact><li>Use whatever lock policy was specified when the database environment
was created.  If no lock policy has yet been specified, set the lock
policy to DB_LOCK_RANDOM.</ul>
<b><a name="DB_LOCK_EXPIRE">DB_LOCK_EXPIRE</a></b><ul compact><li>Reject lock requests which have timed out.  No other deadlock detection
is performed.</ul>
<b><a name="DB_LOCK_MAXLOCKS">DB_LOCK_MAXLOCKS</a></b><ul compact><li>Reject the lock request for the locker ID with the most locks.</ul>
<b><a name="DB_LOCK_MAXWRITE">DB_LOCK_MAXWRITE</a></b><ul compact><li>Reject the lock request for the locker ID with the most write locks.</ul>
<b><a name="DB_LOCK_MINLOCKS">DB_LOCK_MINLOCKS</a></b><ul compact><li>Reject the lock request for the locker ID with the fewest locks.</ul>
<b><a name="DB_LOCK_MINWRITE">DB_LOCK_MINWRITE</a></b><ul compact><li>Reject the lock request for the locker ID with the fewest write locks.</ul>
<b><a name="DB_LOCK_OLDEST">DB_LOCK_OLDEST</a></b><ul compact><li>Reject the lock request for the locker ID with the oldest lock.</ul>
<b><a name="DB_LOCK_RANDOM">DB_LOCK_RANDOM</a></b><ul compact><li>Reject the lock request for a random locker ID.</ul>
<b><a name="DB_LOCK_YOUNGEST">DB_LOCK_YOUNGEST</a></b><ul compact><li>Reject the lock request for the locker ID with the youngest lock.</ul>
<br></ul>
<br>
<br><b>Errors</b>
<p>The DB_ENV-&gt;set_lk_detect method
may fail and return one of the following non-zero errors:</p>
<br>
<b>EINVAL</b><ul compact><li>An
invalid flag value or parameter was specified.</ul>
<br>
<hr size=1 noshade>
<b>Description: DB_ENV-&gt;get_lk_detect</b>
<p>The DB_ENV-&gt;get_lk_detect method returns the deadlock detector configuration.</p>
<p>The DB_ENV-&gt;get_lk_detect method may be called at any time during the life of the
application.</p>
<p>The DB_ENV-&gt;get_lk_detect method
returns a non-zero error value on failure
and 0 on success.
</p>
<b>Parameters</b> <br>
 <b>lk_detectp</b><ul compact><li>The DB_ENV-&gt;get_lk_detect method returns  the
deadlock detector configuration in <b>lk_detectp</b>.</ul>
<br>
<hr size=1 noshade>
<br><b>Class</b>
<a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/lock_class.html">DB_LOCK</a>
<br><b>See Also</b>
<a href="../api_c/lock_list.html">Locking Subsystem and Related Methods</a>
</tt>
<table width="100%"><tr><td><br></td><td align=right>
<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<p><font size=1>Copyright (c) 1996,2008 Oracle.  All rights reserved.</font>
</body>
</html>
